The use of carbon dioxide fiberoptic laser catheter for atrial septostomy

Excimer laser ablation for valvular angioplasty in pulmonary atresia and intact ventricular septum

BACKGROUND AND OBJECTIVES

The prognosis for infants with pulmonary atresia and intact ventricular septum (PA/IVS) is poor and they present a major management challenge. Mechanical penetration of the atretic pulmonary valve is an applicable option for decompression of the right ventricle and optimization of left ventricular function. The utilization of laser energy for debulking and vaporization of the atretic valve tissue is a relevant approach due to the potential for controlled, precise mode of energy distribution.

STUDY DESIGN/PATIENTS AND METHODS

A 4-month-old female with PA/IVS whose failure to thrive was accompanied by critical hemodynamic abnormalities received successful percutaneous pulmonary valve plate ablation by a 0.9 mm pulsed-wave ultraviolet excimer laser catheter (308 nm wavelength, fluence 50 mJ/mm(2); 30 Hz). A "step-by-step" lasing technique was applied whereby the tip of the emitting laser catheter is advanced ahead of a guide wire that serves mainly as support for positioning of that catheter.

RESULTS

Adequate penetration of the atretic tissue enabled introduction of balloon dilations resulting in patency of the atretic valve, decompression of the right ventricle, improved right and left ventricular hemodynamics, and oxygenation. To further investigate the effect of excimer laser energy on atretic valvular tissue this laser was applied in a specimen of heart from an infant who died because of PA/IVS. Histopathologic examination of the irradiated tissue revealed no laser-induced injury to the pulmonary valve.

CONCLUSIONS

Thus, laser ablation and penetration of an atretic pulmonary valve is feasible and safe. The penetration of the atretic valve with the laser catheter enables subsequent introduction of various sizes balloon dilations. The application of available laser sources for treatment of congenital heart diseases is reviewed.

Radiofrequency perforation in the treatment of congenital heart disease

Catheter-directed perforation of cardiac tissue with radiofrequency (RF) energy has expanded the horizon of the interventional cardiologist dealing with congenital heart disorders. The focus of the following discussion will be to detail the biophysical basis behind RF perforation and review its application in the management of congenital heart lesions.

Clinical evaluation criteria for the assessment of impaired pain sensitivity by thulium-laser evoked potentials

OBJECTIVES

Cortical potentials evoked by carbon dioxide laser pulses have been applied in clinical practice to study nociceptive pathways for several years. In this study, we evaluate the properties of an infrared laser (thulium-YAG) with a penetration depth in the skin that matches the intracutaneous depth of nociceptors.

METHODS

Temperature measurements and modelling showed that the thulium laser generates painful intracutaneous temperatures with less surface heating than the carbon dioxide laser and with no side effects (up to 600 mJ pulse energy). To develop clinical evaluation criteria, laser-evoked potentials (LEPs) were recorded from 3 midline positions (Fz, Cz, Pz) versus linked earlobes in 23 healthy subjects. Within a session, two skin areas were studied twice in a balanced sequence using randomized interstimulus intervals and two intensities in randomized order.

RESULTS

After hand and foot stimulation with 540 mJ pulses, all subjects showed reproducible biphasic vertex potential, consisting of a negativity (hand: 210 ms, foot: 250 ms) and a positivity (hand: 330 ms, foot: 380 ms). Mean habituation of the vertex potential amplitude across runs was 25% (hand) or 16% (foot); due to the balanced sequence it did not affect the other comparisons. Following foot stimulation, peak latencies were significantly longer (by 40-50 ms) and amplitudes were significantly smaller than following hand stimulation (22.5+/-6.7 vs. 30.3+/-10.9 microV, mean+/-SD). Using 2. 5 standard deviations from the mean as a cut-off, absolute normative values were determined for peak latencies and amplitudes. In addition, relative normative values were determined for paired comparisons (hand-hand, foot-foot, hand-foot).

CONCLUSIONS

The thulium-YAG laser is a useful tool for assessment of impaired pain sensitivity. Representative case reports illustrate that unlike for early SEP components, the most frequent LEP abnormalities were amplitude differences.

Cardiovascular applications of laser technology

Laser technology has been evaluated for the treatment of coronary artery disease, ventricular and supraventricular arrythmias, hypertrophic cardiomyopathy, and congenital heart disease. Developments in laser angioplasty, laser thrombolysis, transmyocardial laser revascularization, photochemotherapy, laser treatment of arrhythmias and/or laser diagnostics are directed at improving upon conventional non-laser approaches, and providing new therapeutic and diagnostic options. This review will summarize the current status of the multiple applications of laser technology for cardiovascular diagnosis and therapy.